> ## Documentation Index
> Fetch the complete documentation index at: https://docs.galtea.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Tool Correctness

> Measures whether the agent called exactly the expected set of tools for a test case, penalizing missing required tools or using any unnecessary ones.

The Tool Correctness metric is one of the [Deterministic Metric](/concepts/metric) Galtea exposes to objectively verify that an agent used the correct tools for a test case. It is most appropriate when you expect the agent to call a specific set of tools (e.g., function/tool-calling workflows), and you want to penalize missing required tools or the use of any unnecessary ones.

## Evaluation Parameters

To compute the `Tool Correctness` metric, the following parameters are required:

* **`tools_used`**: The tools used by the agent. This evaluation parameter is automatically extracted from the `traces` parameter.
* **`expected_tools`**: The reference (or gold) list of tools to compare against.

## How Is It Calculated?

Conceptually, Tool Correctness is computed as:

1. **Parse Inputs**\
   Read `tools_used` (the tools the agent actually called) and `expected_tools` (the tools required by the test case). Typically, `expected_tools` is specified by the user when creating the test case, while `tools_used` is populated automatically from execution traces captured via Galtea’s [@trace](/sdk/tutorials/tracing-agent-operations) decorator.

2. **Normalize and Dedupe Tool Names**\
   Normalize tool identifiers (e.g., sanitize formatting and strip equivalent prefixes) and deduplicate by canonical name so repeated calls do not affect the result.

3. **Final Score**\
   Tool Correctness returns a value of **0** or **1** in this implementation:
   * **1** – The agent called all expected tools and no unnecessary ones (order and duplicates ignored).
   * **0** – The agent missed at least one expected tool or called at least one extra tool.

## Suggested Test Case Types

Use Tool Correctness when you want to verify tool-calling behavior, such as:

* **Tool-Required Tasks** where specific tools must be invoked.
* **Agent Workflow Validation** where using an extra tool is considered incorrect or risky.
* **Regression Tests** for agents to ensure they keep calling the same required tools after prompt/model changes.
* **Safety/Policy-Gated Flows** where unexpected tool usage should fail the evaluation.